[antlr-interest] Explanation about EOF needed

[`VL]

Hello.

I'm trying to include comments information into my grammar and have
some problems.
Below is the minimal example i have:

========== Cut =================
grammar simple;

// the whole thing: all stuff till the end of file
prog :   commented_kw+ EOF;

// Keyword with optional comment before it or just comment or empty line
commented_kw: COMMENT* varspec* NL;

// key=val
varspec: TKN '=' (TKN);

// token for keys and values
TKN:  ('a'..'z'|'A'..'Z'| '0'..'9')+;

// newline separator
NL : '\n' ;

// whitespace are thrown away
WS:     (' '|'\t'| '\r')+ { $channel=HIDDEN; };

// comment goes till end of line, including it
COMMENT : (' '|'\t')* ( '#' (~'\n')*  ) NL;
========== Cut =================

Here is the input (generic configuration file):

========== Cut =================


# This is one-line comment (global for file)

# This is many one-line comments (global)
# This is many one-line comments (global)
# This is many one-line comments (global)
# This is many one-line comments (global)

# This is comment to var
var=value

# This is comment to many vars
var=value var=value var=value

var=value
# After-var comment

# Pre-Var 1
# Pre-Var 2
# Pre-Var 3
var=value
# After-Var 1
# After-Var 2


# LAST LINE - no newline at the END
========== Cut =================

Everything goes fine, except i'm getting
MismatchedTokenException(0!=0) on the last line.

Well, using such grammar it is expected error, since my comment is
defined to end with NL
and it can't be found.

I tried to modify COMMENT lexer rule to end with (NL|EOF). No effect.
But i have one more
required NL, in commented_kw rule, i changed it to (NL|EOF), and got
error about unreachable
alternative in 'prog' rule. I tried a lot of more variants, trying to
move COMMENT rule into parser
level and more, but i can't understand what's going on.

I'm satisfied with first variant of grammar, but it gives me an error.
How should i modify it to
make it work? Where is my error when i tried to achive my goals?

Thanks.